#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int Feibo(int n)
{
	if (n == 1 || n == 2)
	{
		return 1;
	}
	else
	{
		return Feibo(n - 1) + Feibo(n - 2);
	}

}
int main()
{
	int n = 0;

	scanf("%d", &n);

	printf("%d", Feibo(n));

	return 0;
}